1. Field of the Invention
This invention relates to dihydrofuran derivatives and, more specifically, to certain 2,4,5-substituted-2,3-dihydrofurans which are useful fragrance compounds.
2. Description of the Prior Art
The use of synthetic fragrance chemicals has added a new dimension to the art of perfumery. As a result of the development of new synthetic perfume chemicals, perfumers have greater flexibility in developing fragrance formulations and are better able to mimic natural aromas. However, as perfumers become more adept in the use of synthetic materials for the formulation of sophisticated fragrances and developing the subtle nuances typically associated with natural fragrances, there is a growing demand for new synthetic fragrance compounds.
Furan derivatives are known to have desirable fragrance and flavor qualities. For example, Ethyl furoate, n-amyl furoate, ethyl furyl .beta.-hydroxypropionate and furfural are reported for use in perfumes, cosmetics and soaps. Furfuryl alkyl and aryl ethers are disclosed as flavor enhancers in U.S. Pat. No. 3,940,502. Tetrahydrofurans are also disclosed for fragrance applications. U.S. Pat No. 3,668,134 discloses the use of esters or ethers of tetrahydrofurans as perfumery ingredients for detergent compositions. 3-Oximino-4-oxo-2,5-dimethyltetrahydrofuran is described in U.S. Pat. No. 4,116,982 and disclosed to have a fine caramel-like fragrance making it useful for the manufacture of scents and flavors. U.S. Pat. No. 3,470,209 discloses 2-acetonyl-3,5-dimethyl-5-isopropyl-tetrahydrofuran as having a pleasant spicy odor reminiscent of bay and eucalyptus. 2-(1'-Hydroxymethyl-ethyl)-5-methyl-5-vinyl-tetrahydrofuran is disclosed in U.S. Pat. No. 3,764,567 as a useful ingredient for incorporation in floral perfumes. In U.S. Pat. No. 3,227,731 carbonates of 1-(.alpha.-furyl)-2,2-dialkyl-1,3-dihydroxypropanes and 1-(.alpha.-tetrahydrofuryl)-2,2-dialkyl-1,3-dihydroxypropanes are indicated to be useful in perfume compounding.
2,3-Dihydrofurans having a vinyl group at the 2-position, a lower carboxylate radical at the 4-position and a methyl group at the 5-position have been reported in Chemical Abstracts, Volume 75, 87758y (1971); Volume 93, 71095r (1980); Volume 93, 239112v (1980); and Volume 94, 15458v (1981). Additionally, in Chemical Abstracts Volume 96, 52099r (1982), substituted 2,3-dihydrofurans obtained by the oxidative addition of 1,3-dicarbonyl compounds with dienes in the presence of manganese (III) and copper (II) acetates are reported. None of the reported 2,3-dihydrofurans have a higher alkyl group substituted in the 5-position and there is no indication that any of the compounds have useful fragrance qualities.